Thermal diffusivity of natural and synthetic garnet solid solution series

Abstract

Knowledge of heat transport properties as a function of mineral-and rock-composition and temperature is of major relevance to understand and model heat transfer in the Earth's interior. A systematic study on 13 natural and 4 synthetic garnets was carried out in an attempt to obtain a better systematic understanding of the processes that affect the heat transport in minerals, especially the effect of chemical substitution in solid solution series. It is found that substitution significantly lowers the thermal diffusivity from end-member values for both synthetic and natural garnets with a minimum of thermal diffusivity at an intermediate composition. The thermal diffusivity as a function of the degree of substitution can be described by the approach of Padture and Klemens (1997). With increasing temperature the thermal diffusivity decreases due to phononphonon-scattering effects. A quantitative analysis of the high-temperature behaviour was carried out by using the model of Roufosse and Klemens (1974), which takes a lower limit of thermal diffusivity at elevated temperatures into account. The model allows for an extrapolation of the deduced room temperature thermal diffusivities to higher temperatures. Furthermore, the model was modified to determine the high temperature limit of the thermal diffusivity for all investigated natural garnets D min to be 0.64±0.03 mm 2 /s.

Thermal diffusivity of a SNAB glass system doped with CdS nanocrystals and Nd3+

“…Figure 5 shows thermal diffusivity as a function of the concentration (X) of SNAB + XNd 2 O 3 (wt.%). The decrease of D as Nd 3+ concentrations increase may be attributed to additional variations of local density due to different atoms and vacancies, especially oxygen, which is known to efficiently scatter elements [25,[28][29][30]. Similar results were observed in Yb 3+ doped laser crystals [25].…”

Thermal diffusivity of MORB-composition rocks to 15 GPa: implications for triggering of deep seismicity

“…This is consistent with the predicted pressure dependence of thermal diffusivity of Hofmeister (2007). Furthermore, a recent study (Marquardt et al, 2009) surveyed the thermal diffusivities of a wide range of natural and synthetic garnets at atmospheric pressure and concluded that, in the high-temperature limit, they all had the same value of thermal diffusivity, D min , of 6.4(3) x 10 -7 m 2 /s. This compares very well with the present high-temperature limit value of 6.2(5) x 10 -7 m 2 /s and gives us confidence that the present results for MORB composition majorite at 15 GPa are robust.…”

Investigation of thermal diffusivity dependence on temperature in a group of optical single crystals doped with rare earth ions

“…The influence of temperature and dopants on phonon velocities, both longitudinal and transverse, can be neglected [7,[13][14][15]. Thus, changes in the thermal diffusivity, caused by these factors, are almost completely defined by the changes in the mean free path of phonons.…”